Sources of infrared radiation are widely used in instrumentation such as spectroscopy and capnographs (e.g., CO2 sensors) but, to date, have all been resistive type sources which are frequency limited and exhibit a high thermal mass. In the prior art, pulsing the infrared radiation source was accomplished either with a mechanical chopper wheel or a scanning mirror placed in front of the source; or by alternately energizing and deenergizing the filament. Besides the disadvantages associated with the many moving parts associated with chopper wheels and the cost of scanning mirrors, there is a limit to the frequencies which can be obtained. Energizing and deenergizing the filament requires high power requirements and, because of the thermal mass of the filament, the frequencies associated with this method are undesirably low for applications such as CO2 gas monitoring, anesthesia gas monitoring, N2O gas monitoring, and tissue spectroscopy.
Electrode lamps are known in the art for visible illumination purposes but they are neither designed to be pulsed at high frequencies nor are they designed as sources of infrared radiation. See, e.g., U.S. Pat. Nos. 4,633,128 and 5,399,931.